from __future__ import annotations

from pathlib import Path

from pypdf import PdfWriter

from pdf2md.ir import WarningCode
from pdf2md.text_fidelity import (
    check_text_fidelity,
    compare_text_pages,
    count_hangul_syllables,
    count_unexpected_cjk,
    hangul_spacing_anomaly_ratio,
    strip_markdown_for_text_fidelity,
)


def test_text_metric_helpers_count_hangul_cjk_and_spacing() -> None:
    assert count_hangul_syllables("응 력 A 曲") == 2
    assert count_unexpected_cjk("응 력 A 曲") == 1
    assert hangul_spacing_anomaly_ratio("응 력") == 1.0
    assert hangul_spacing_anomaly_ratio("응력") == 0.0


def test_markdown_stripping_ignores_math_assets_and_code() -> None:
    markdown = "\n".join(
        [
            "# 제목",
            "![figure](paper.assets/fig.png)",
            "본문 $x_i$ 유지",
            "```",
            "코드 한글",
            "```",
            "`인라인 코드` 마지막",
        ]
    )

    stripped = strip_markdown_for_text_fidelity(markdown)

    assert "제목" in stripped
    assert "본문" in stripped
    assert "마지막" in stripped
    assert "figure" not in stripped
    assert "x_i" not in stripped
    assert "코드 한글" not in stripped
    assert "인라인 코드" not in stripped


def test_compare_text_pages_flags_low_hangul_fidelity_and_replacement_candidate() -> None:
    result = compare_text_pages(
        source_pages=("쉘의 응력과 곡률을 계산한다",),
        markdown_pages=("쉘의 력과 曲률을 계산한다",),
        source_page_start=6,
    )

    page = result.pages[0]
    assert page.comparison_status == "checked"
    assert page.source_page_number == 6
    assert page.pypdf_hangul_count > page.markdown_hangul_count
    assert page.unexpected_cjk_count == 1
    assert page.replacement_candidate is True
    assert [warning.code for warning in result.warnings] == [
        WarningCode.TEXT_LAYER_AVAILABLE,
        WarningCode.TEXT_FIDELITY_LOW,
        WarningCode.UNEXPECTED_CJK_IN_KOREAN_TEXT,
    ]


def test_compare_text_pages_allows_markdown_hangul_count_above_source() -> None:
    result = compare_text_pages(
        source_pages=("응력",),
        markdown_pages=("응력 변형률",),
    )

    assert result.pages[0].hangul_count_ratio == 2.5
    assert result.pages[0].replacement_candidate is False


def test_check_text_fidelity_marks_uncertain_page_mapping_for_multi_page_markdown() -> None:
    result = check_text_fidelity(
        Path("paper.pdf"),
        "첫 페이지와 둘째 페이지를 합친 Markdown",
        page_count=2,
        source_text_pages=("첫 페이지", "둘째 페이지"),
    )

    assert [page.comparison_status for page in result.pages] == [
        "page_mapping_uncertain",
        "page_mapping_uncertain",
    ]
    assert [warning.code for warning in result.warnings] == [
        WarningCode.TEXT_LAYER_AVAILABLE,
        WarningCode.TEXT_PAGE_MAPPING_UNCERTAIN,
    ]


def test_blank_generated_pdf_extraction_is_nonfatal(tmp_path: Path) -> None:
    pdf = tmp_path / "blank.pdf"
    writer = PdfWriter()
    writer.add_blank_page(width=72, height=72)
    with pdf.open("wb") as file:
        writer.write(file)

    result = check_text_fidelity(pdf, "Markdown text", page_count=1)

    assert result.pages[0].comparison_status == "source_text_missing"
    assert result.warnings == ()